Izu-Bonin Trench

a depression in the floor of the Pacific Ocean. It is located along the eastern foot of the Nampo Islands Ridge, which extends from the island of Honshu in a southerly direction to the Bonin Islands. In the north it is joined to the Japan Trench, and in the south it is separated from the Volcano Trench by a tall narrow crest. It is approximately 1,000 km long. The narrow floor of the trench, flat in certain areas, is divided by sills into several closed depressions with depths of 7,000–9,000 m. A maximum depth of 9,810 m was established in 1955 by a Soviet expedition on the ship Vitiaz’.